The long-term objective of this proposal is to generate a cartilage product with mechanical properties comparable to those of adult articular cartilage for the repair of focal articular defects. Based on previous experimental findings, our hypothesis is that mechanical loading will improve the growth of tissue engineered cartilage in vitro, resulting in a cartilage product with biochemical and biomechanical properties similar to those of articular cartilage. Such tissues are expected to withstand the mechanical forces experienced in vivo better than currently available products, increasing the probability of a successful surgical outcome. To this end, the proposed specific aims of this proposal are as follows: Aim 1: Further develop a novel in house uniaxial compression-perfusion bioreactor system designed and used in the SBIR Phase I into a modular, closed, long-term culture system that supports mechanical modulation and testing of tissues. Aim 2: Determine a culture regime (which will include mechanical loading at specified amplitudes, frequencies, and cycles, as well as perfusion) which results in cartilage constructs with biomechanical and biochemical properties comparable to those of adult articular cartilage. Aim 3: Determine the ability of allogeneic tissue engineered cartilage constructs to successfully repair focal defects on the condylar surface of the patellofemoral joint. PROPOSED COMMERCIAL APPLICATION: Tissue engineering of cartilage in vitro, followed by transplantation for human therapy of articular surface defects.